How the best’ hospitals get the best AMI outcomes

A low-tech solution: Aspirin and beta-blockers

Each year in July, U.S. News & World Report publishes a list of "America’s Best Hospitals" modeled on Avedis Donabedian’s three elements for measuring quality — structure, process, and outcome.1

University teaching hospitals routinely score highest, presumably because they have concentrations of clinical expertise, a focus on clinical research, and access to advanced technologies.

However, a recent study provides a low-tech explanation for better acute myocardial infarction (AMI) outcomes found at the "best" hospitals, one that can be implemented at any hospital: More careful adherence to national practice guidelines in the use of aspirin and beta-blocker therapy.2

The authors analyzed data on 150,000 Medi- care AMI patients collected by the Cooperative Cardiovascular Project of the Health Care Financing Administration and found that the top-ranked hospitals had significantly lower risk-adjusted 30-day mortality rates than other hospitals, regardless of whether the other hospitals were similarly equipped. (See chart, p. 104.)

The authors conclude that much of the survival advantage was due to higher use of aspirin and beta-blockers rather than to greater use of high-tech thrombolytic therapy or primary angioplasty.

Aspirin should be immediately given at the time the AMI diagnosis is made, unless there is a specific contraindication such as allergy or recent gastrointestinal hemorrhage. In the second International Study of Infarct Survival, aspirin was found to be nearly as effective as streptokinase, reducing 30-day mortality 23% in 17,000 AMI patients. The benefit was additive in patients receiving both aspirin and streptokinase. Other studies have revealed similar benefit from immediate aspirin therapy.

Beta-blockers make a difference

Early administration of IV beta blockers in nearly 30,000 AMI patients enrolled in 28 randomized trials revealed an average 14% reduction in mortality during the first week of therapy. Reinfarction was reduced 18%. Beta-blocking agents reduce infarct size by reducing heart rate, blood pressure, and myocardial contractility, all of which diminish myocardial oxygen demand.

Only about 40% of AMI patients are ideal candidates for the immediate use of IV beta-blocker therapy because of relative contraindications including hypotension, bradycardia, asthma, and chronic obstructive pulmonary disease.

The benefits in short-term mortality by using aspirin and beta-blockers have been clearly shown in several randomized clinical trials. It is clear from TheNew England Journal of Medicine study that on average, even the top-ranked hospitals fail to reach the goal of 100% compliance. That goal is possible however, because the authors report some of the similarly equipped and non-similarly equipped hospitals did reach 100% compliance.

[The preceding article was first published in the April 1999 issue of The Assertive Utilization and Quality Report — $60 per year (12 issues). For more information, contact Elgin Kennedy, MD, 204 Second Ave., No. 334, San Mateo, CA 94401. Telephone: (415) 348-3647.]

Editor’s note: The author of this article suggests that a way to improve quality and cost-effectiveness at your hospital is to conduct an audit of your last 30 patients who were discharged with the diagnosis of AMI. Determine the percentage of patients who received aspirin within 30 minutes of admission to the ED, and determine the percentage of patients who received aspirin at any time during their stay there. You might also study the use of IV beta-blocker therapy in ideal candidates.

The ACC/AHA guideline for the management of patients with acute myocardial infarction, the AHCPR guideline for diagnosis and management of unstable angina, and the national guideline for coronary artery disease with myocardial infarction can all be found at The National Guideline Clearinghouse, a comprehensive database of evidence-based clinical practice guidelines and related documents produced by the Agency for Health Care Policy and Research in partnership with the American Medical Association and the American Association of Health Plans: www.guideline.gov. For example, the ACC/AHA guideline states for aspirin therapy:

• Class I(Conditions for which there is evidence for and/or general agreement that a given procedure or treatment is beneficial, useful, and effective): A dose of 160 to 325 mg should be given on Day 1 of acute MI and continued indefinitely on a daily basis thereafter.

• Class IIb (Usefulness/efficacy is less well established by evidence/opinion): Other antiplatelet agents such as dipyridamole or ticlopidine may be substituted if true aspirin allergy is present.

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